Shortage of Forage Fibre and Bicarb Exacerbating Acidosis Problems 2010-12-09

A lack of good quality first cut silage, low forage fibre levels and a national shortage of sodium bicarbonate mean that many farmers are struggling with acidiosis problems this winter.

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Last year, reports from DairyCo indicated that as many as half of all UK dairy cows are thought to be suffering from sub-acute ruminal acidosis (SARA) and consultants stress the problem is no better this year.

“It is very difficult to get enough long fibre into cows this year,” says AB Vista technical director Dr Derek McIlmoyle. “Many grass silages are variable in quality with low NDF levels common, while maize silages are generally good quality with relatively high levels of starch. Straw as a source of long fibre is scarce too, and very expensive, and all these factors are contributing to widespread acidosis problems. And now that the rumen buffer sodium bicarbonate is in short supply too, the problems are only being exacerbated.”

Dr McIlmoyle says that many farmers look to introduce sodium bicarbonate to the diet to try and mitigate acidosis problems, but points out that such a rapidly soluble rumen buffer may not necessarily be the best solution.

“The immediate response to an acidosis problem is to reach for a buffer, usually sodium bicarbonate, for inclusion in the feed. However, in a TMR diet rich in wet silage, sodium bicarbonate can lose its effects as early as in the feeder wagon and can therefore be unable to influence rumen pH,” he says.

“Inclusion in compound does provide some protection, but even with out-of-parlour feeding systems, conventional soluble buffers included within concentrate feeds react very quickly when they reach the rumen. This means their benefits are lost long before the acidity really starts to increase as the rumen fermentation proceeds.”

Dr McIlmoyle advocates the use of a rumen conditioner rather than a straight soluble buffer. “Specialist rumen conditioners like Acid Buf only break down when acid levels rise. This means its inclusion in the main ration will not adversely affect non acidotic cows, but will prevent rumen pH falling below 5.5 in milkers suffering an acidosis challenge.

“The feedback on the inclusion of Acid Buf has been very positive where it has been used to help farmers overcome low forage fibre level and feed higher levels of cereals. It’s a slow release rumen conditioning product and is particularly useful at holding rumen pH within the optimum range. Its use helps the rumen microbes to produce the right balance of VFAs (propionate and acetate) for maximum milk output and quality across the whole herd.”

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